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Hyperbranched polyurethanes with varying spacer segments between the branching points

Kumar, Anil and Ramakrishnan, S (1996) Hyperbranched polyurethanes with varying spacer segments between the branching points. In: Journal of Polymer Science Part A: Polymer Chemistry, 34 (5). pp. 839-848.

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Hyperbranched polyurethanes, with varying oligoethyleneoxy spacer segments between the branching points, have been synthesized by a one-pot approach starting from the appropriately designed carbonyl azide that incorporates the different spacer segments. The structures of monomers and polymers were confirmed by IR and H-1-NMR spectroscopy. The solution viscosity of the polymers suggested that they were of reasonably high molecular weight. Reversal of terminal functional groups was achieved by preparing the appropriate monohydroxy dicarbonyl azide monomer. The large number of terminal isocyanate groups at the chain ends of such hyperbranched macromolecules caused them to crosslink prior to its isolation. However, carrying out the polymerization in the presence of 1 equiv of a capping agent, such as an alcohol, resulted in soluble polymers with carbamate chain ends. Using a biphenyl-containing alcohol as a capping agent, we have also prepared novel hyperbranched perbranched polyurethanes with pendant mesogenic segments. These mesogen-containing polyurethanes, however, did not exhibit liquid crystallinity probably due to the wholly aromatic rigid polymer backbone. (C) 1996 John Wiley & Sons, Inc.

Item Type: Journal Article
Publication: Journal of Polymer Science Part A: Polymer Chemistry
Publisher: John wiley and sons
Additional Information: Copyright of this article belongs to John Wiley and Sons.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 03 May 2011 08:03
Last Modified: 03 May 2011 08:03
URI: http://eprints.iisc.ac.in/id/eprint/37289

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